#7349 HIGH 8.2.0 (: Pango rendering performance

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#7349: Pango rendering performance
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 Reporter:  bert            |       Owner:  etoys               
     Type:  defect          |      Status:  new                 
 Priority:  high            |   Milestone:  8.2.0 (was Update.2)
Component:  etoys-activity  |     Version:  Git as of bug date  
 Keywords:                  |    Verified:  0                   
 Blocking:                  |   Blockedby:                      
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 One reason for the performance degradation is that the Pango rendering
 methods flush the whole screen. That is, for every little string there  is
 a BitBlt of 1200x900 pixels converting from 32 to 15 bpp. To only flush
 the affected area, you need to give a rectangle parameter to #finish:.

 Also, for each string/paragraph it actually allocates, draws into, and
 discards a 1200x900x32 Cairo bitmap surface. I did not measure how
 expensive that is, but it could be avoided by reusing one Cairo
 surface for all rendering (the affected region will have to be cleared in
 between of course).

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Ticket URL: <http://dev.laptop.org/ticket/7349>
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